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Mail was unable to open this mailbox on the server “”. The server returned the error: Mailbox does not exist, or must be subscribed to

After I upgraded to mongerey this error occurs in my email all the time, my previous was mojave.

I did everything like deleting mails from the libraries, reload etc.

MacBook Air 13″, macOS 12.0

Posted on Dec 9, 2021 11:49 PM

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Question marked as Top-ranking reply

Posted on Dec 10, 2021 9:48 AM

Something must have gotten corrupted during the upgrade's download. It sounds like you may have to go into your email app and (1) cancel the account, and (2) set up a new account which can then access the email provider's server.

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Mail was unable to open this mailbox on the server “”. The server returned the error: Mailbox does not exist, or must be subscribed to

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